Origin and history of duke

Old English eorl "brave man, warrior, leader, chief" (contrasted with ceorl "churl"), from Proto-Germanic *erlaz, which is of uncertain origin. In Anglo-Saxon poetry, "a warrior, a brave man;" in later Old English, "nobleman," especially a Danish under-king (equivalent of cognate Old Norse jarl), then one of the viceroys under the Danish dynasty in England. After 1066 adopted as the equivalent of Latin comes (see count (n.1)).

Earl Grey tea (1880s) was originally a Chinese tea blended with bergamot oil, supposedly from a recipe given to Charles, second Earl Grey (the Whig prime minister), in the 1830s, but perhaps it was named later, commercially, in his honor.

1520s, from French archeduc (Modern French archiduc), from Merovingian Latin archiducem (c. 750); see arch- + duke (n.). Formerly the title of the rulers of Austrasia, Lorraine, Brabant, and Austria; later the titular dignity of the sons of the Emperor of Austria. Related: Archducal; archduchy.